using System;

using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Asn1.X509;

namespace Org.BouncyCastle.Asn1.Cms
{
	public class KekRecipientInfo
		: Asn1Encodable
	{
		private DerInteger			version;
		private KekIdentifier       kekID;
		private AlgorithmIdentifier keyEncryptionAlgorithm;
		private Asn1OctetString     encryptedKey;

		public KekRecipientInfo(
			KekIdentifier       kekID,
			AlgorithmIdentifier keyEncryptionAlgorithm,
			Asn1OctetString     encryptedKey)
		{
			this.version = new DerInteger(4);
			this.kekID = kekID;
			this.keyEncryptionAlgorithm = keyEncryptionAlgorithm;
			this.encryptedKey = encryptedKey;
		}

		public KekRecipientInfo(
			Asn1Sequence seq)
		{
			version = (DerInteger) seq[0];
			kekID = KekIdentifier.GetInstance(seq[1]);
			keyEncryptionAlgorithm = AlgorithmIdentifier.GetInstance(seq[2]);
			encryptedKey = (Asn1OctetString) seq[3];
		}

		/**
		 * return a KekRecipientInfo object from a tagged object.
		 *
		 * @param obj the tagged object holding the object we want.
		 * @param explicitly true if the object is meant to be explicitly
		 *              tagged false otherwise.
		 * @exception ArgumentException if the object held by the
		 *          tagged object cannot be converted.
		 */
		public static KekRecipientInfo GetInstance(
			Asn1TaggedObject	obj,
			bool				explicitly)
		{
			return GetInstance(Asn1Sequence.GetInstance(obj, explicitly));
		}

		/**
		 * return a KekRecipientInfo object from the given object.
		 *
		 * @param obj the object we want converted.
		 * @exception ArgumentException if the object cannot be converted.
		 */
		public static KekRecipientInfo GetInstance(
			object obj)
		{
			if (obj == null || obj is KekRecipientInfo)
				return (KekRecipientInfo)obj;

			if(obj is Asn1Sequence)
				return new KekRecipientInfo((Asn1Sequence)obj);

			throw new ArgumentException("Invalid KekRecipientInfo: " + obj.GetType().Name);
		}

		public DerInteger Version
		{
			get { return version; }
		}

		public KekIdentifier KekID
		{
			get { return kekID; }
		}

		public AlgorithmIdentifier KeyEncryptionAlgorithm
		{
			get { return keyEncryptionAlgorithm; }
		}

		public Asn1OctetString EncryptedKey
		{
			get { return encryptedKey; }
		}

		/**
		 * Produce an object suitable for an Asn1OutputStream.
		 * <pre>
		 * KekRecipientInfo ::= Sequence {
		 *     version CMSVersion,  -- always set to 4
		 *     kekID KekIdentifier,
		 *     keyEncryptionAlgorithm KeyEncryptionAlgorithmIdentifier,
		 *     encryptedKey EncryptedKey
		 * }
		 * </pre>
		 */
		public override Asn1Object ToAsn1Object()
		{
			return new DerSequence(version, kekID, keyEncryptionAlgorithm, encryptedKey);
		}
	}
}
